Mission: Apply social and behavioral science methods to the interdisciplinary investigation of HIV/AIDS to improve its understanding, prevention, and treatment and improve the quality of life of persons living with HIV/AIDS. Aim 1. Increase the utility and efficiency of HIV/AIDS research by providing behavioral science research services and methods to CFAR Investigators (and other users). Aim 2. Establish research partnerships between CFAR Investigators (and other users) and behavioral scientists to increase interdisciplinary HIV/AIDS. Aim 3. Offer training and advocacy to students, new investigators, trainees, agencies, community, and consumers to increase behavioral science research knowledge, skills, and human subject protection in HIV/AIDS research. Added-value: The Core supported 202 users in 2007 compared to 39 users in 2006 - where 42% of users were CFAR investigators in 2007 versus 12.5% in 2006. Scientific discoveries and public health relevance include: Behavioral/epidemiological research involving discordant couples in Zambia led to important insights into HIV transmission;research on injection drug users in China led to HIV prevention policy changes;effective sexual risk reduction strategies among adolescents have been developed to prevent future HIV transmission;motivational readiness guide effective sexual risk reduction interventions;first behavioral treatment for injection drug use and HIV risk reduction effectively transported to Ukraine;and unique barriers to HIV/AIDS treatment were discovered among rural African American women.